What Role Does Aerobic Capacity Play in Successful Aging?

What Role Does Aerobic Capacity Play in Successful Aging?

(Last Updated On: April 5, 2019)

You can’t stop the aging process but you can slow it down. We all age a little differently, partially based on our own unique genetics but also based on lifestyle habits and exposures. You’ve probably seen people in their 70s who have the energy and vitality of a 30-year old and 40-year old’s who look and act like their going on 60. One lifestyle factor linked with healthy aging is exercise, both strength training, and aerobic exercise. As you know, you lose strength and muscle size after the age of 30 and that contributes to age-related decline later on in life – but what about aerobic capacity? What role does it play in successful aging?

What is Aerobic Capacity?

Loosely speaking, aerobic capacity is the ability to sustain an oxygen-requiring activity for a longer period of time. For example, a person with a higher aerobic capacity is less likely to become winded when they walk up a steep hill than someone with a more modest aerobic capacity. V02 max is the term used to describe aerobic capacity in the medical and fitness community.

To measure aerobic capacity, a person would get on a treadmill or ergometer and run or pedal as the height or resistance is gradually increased. As the incline gets higher, your heart, lungs, and blood vessels have to work harder to deliver oxygen to your muscles as the demand for oxygen rises. At some point, your body’s ability to deliver oxygen to your muscles plateaus and you have to stop. The point where that occurs is your V02 max.

How V02 Changes with Age

Just as you lose muscle strength and mass with age, your aerobic capacity goes down. Studies show that V02 max declines by 10-15% per decade after the age of 50 but some studies suggest that the decline may be faster, as high as 20% per decade. You might wonder why that’s important, especially if you don’t plan on running a marathon. It matters. Research shows that aerobic capacity is strongly correlated with successful aging. If you think about what determines aerobic capacity, it’s not hard to see why.

One determinant of aerobic capacity is the ability of your heart to deliver oxygen to your muscles and tissues. During exercise, your heart rate goes up as the intensity of the exercise increases, until it reaches a maximum where it can’t increase anymore. This is referred to as your maximal heart rate. You can get a rough measure of what your maximum heart rate is by subtracting your age from 220. For example, a 50-year-old has a theoretical maximum heart rate of 170. As it turns out, this formula isn’t a particularly reliable measure of maximal heart rate and there are other formulas that may be more reliable.

Regardless of the formula you use, your maximum heart rate goes down with age. This means your heart rate plateaus earlier during progressive aerobic exercise, meaning oxygen delivery reaches a peak and you poop out sooner due to inadequate oxygen delivery to your muscles. One reason your heart rate increases during exercise is because your adrenal glands release catecholamines, chemicals that increase your heart rate. As you age, your heart becomes less responsive to these chemicals and heart rate doesn’t increase as much.

To get the oxygen to muscles when you exercise, you also need healthy blood vessel function, including the tiny capillaries that carry blood and oxygen directly to your muscle fibers. Blood vessel function also declines to a varying degree with age as your arteries become stiffer and, in some cases, filled with plaque. This happens much faster in people who have untreated high blood pressure.

Other Organs That Affect Aerobic Capacity

In addition, your lungs have to be able to take up oxygen from the outside so that it enters your bloodstream and is delivered to your muscles. If you have certain types of lung disease, you can’t do that. Another factor is how readily oxygen can travel from capillaries into the muscle tissue and, ultimately, into the mitochondria that use it to make ATP. The ability for oxygen to cross the capillary and enter the muscle also goes down somewhat with age. Plus, you lose muscle mass as you age and that further contributes to a drop in V02 max.

Considering these factors, it’s easy to say how a high aerobic capacity is correlated with healthy aging. To be able to deliver oxygen to tissues efficiently during exercise, you need a good heart, blood vessel, and lung function. These are also important for health and longevity. So, the same factors that give you the capacity to deliver oxygen to your muscles efficiently are also correlated with good health.

Does this hold up in practice? Yes, research shows people with low aerobic capacity have a faster rate of decline with age and a higher mortality rate. Studies in specially bred rats reveal the same. Mice bred to have a low aerobic capacity have inferior heart health compared to those with high aerobic capacity. Makes sense, doesn’t it? A low V02 max affects the quality of life in another way. If you have a poor aerobic capacity, you have less stamina and become tired more easily.

In one study, researchers followed a group of men for almost 50 years. They divided them into three groups – those with low aerobic capacity, those with medium aerobic capacity, and those with high aerobic capacity. Those with low aerobic capacity had a 42 percent higher risk of death compared to guys with high aerobic capacity. In fact, low aerobic capacity ranked just below smoking as a risk factor for early death. The take-home message? Being out-of-shape is bad for your long-term health.

Physical Activity is Good Medicine

You can’t completely stop the age-related decline in aerobic capacity but training that increases your heart rate helps preserve your fitness level and slow the decline. In fact, a study of Japanese centenarians found that the health and independence of these long-living men and women was directly correlated with how physically active they were. This likely applies to you too. You need strength training to preserve muscle tissue and strength AND aerobic exercise to help preserve your aerobic capacity. For doing this, vigorous exercise appears to be better – so think high-intensity interval training rather than a leisurely walk.

How much of your aerobic capacity can you preserve? There’s some evidence that Master’s level athletes who continue to train at a high intensity, retain most of their aerobic capacity. That should be encouragement enough to stay active!